Lesson 2 radio
Task 1. Read paragraphs 1 and 2 of the article and answer these questions.
How does radio work?
Why do we need an antenna?
Do radio waves exist in nature?
Task 2.Match these words from the article to their definitions.
electromagnetic field a) group of stars
frequency b) to send
satellite c) measurement of the number of occurrences of
a repeated event per unit of time
constellation d) to connect
to transmit e) enormous
to link f) sputnik
huge g) physical field produced by electrically charged
objects
Task 3. Read the article and complete the chart.
Wireless takes many forms
Radios work by using the electromagnetic spectrum to send information. When an electrical current travels through a wire it creates an electromagnetic field, sending out waves in all directions—rather like light, which is also a part of the spectrum but at much higher frequencies. An antenna and extra power allow the signal to be transmitted over long distances. The frequency of the wave can be changed so that signals do not interfere with one another, allowing more of the spectrum to be used.
Radio waves exist in nature, from sound and light to cosmic rays in space. The man-made sort can do things like transmit music or heat food in a microwave. At the low end of the spectrum are the frequencies used for things like television and mobile phones. The lower the frequency of the wave, the farther it can travel or penetrate physical objects. Thus FM radio at relatively high frequencies is used for local stations but does not travel far, whereas short-wave radio, at low frequencies, can stretch around the world.
Wireless technology can be split into five main sorts, roughly ranked by the distance that the signals travel. The top travellers are satellite communications such as the Global Positioning System (GPS). This is a constellation of 24 satellites, managed by the American armed forces, that constantly send out signals to devices on the ground. But the signals travel only one way, from satellite to device.
A little closer to home, and with signals going both ways, are “wide-area” mobile-phone technologies such as GSM or CDMA. Advanced “third-generation” (3G) versions include HSDPA* and LTE*, developed by the mobile-phone industry. A promising rival is WiMax, based on the Internet standard and supported by the computer industry. A third category takes in shorter-range signals used to connect things in a building or room. Examples include the popular Wi-Fi standard to access the Internet in hotels or airports, and Zigbee to link sensors. A new advance is ultra-wideband (UWB) technology, which uses very high frequencies at very short range to transmit huge amounts of data, as in sending video from an iPod-like device to a TV screen.
A fourth type connects things in a “personal-area network” or PAN. An example is Bluetooth, which is used to link mobile phones with earpieces. The last is near-field communications (NFC), where contact needs to be close, as in passes for buildings and public transport. A variant is radio-frequency identification (RFID) tags used by retailers and others.
* HSDPA - High-Speed Downlink Packet Access
* LTE - Long Term Evolution
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Abbreviation |
Meaning |
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1. GSM |
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2. UWB |
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3. PAN |
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4. NFC |
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5. RFID |
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Task 4.Find words or phrases in the text which mean the following:
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1. intersect |
(paragraph 1) |
interfere |
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2. diapason |
(paragraph 1) |
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3. device allows you to heat your food |
(paragraph 2) |
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4. divided into |
(paragraph 3) |
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5. consist of |
(paragraph 4) |
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6. competitor |
(paragraph 4) |
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7. seller |
(paragraph 5) |
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Task 5. Which of these statements are true? Correct the false ones.
The frequency of the wave can be changed.
The higher the frequency of the wave, the farther it can travel or penetrate physical objects.
Wireless technology can be split into four main sorts.
Ultra-wideband (UWB) technology is a new advance.
Bluetooth is used to link mobile phones with earpieces.
Radio-frequency identification (RFID) tags are used by retailers.
Task 6. Watch the video “How Satellite Radio Works” and retell the main work principles of a satellite radio.
Task 7. Read the article and answer the questions.
What does a wireless device refer to?
What resources can a computer on the network share?
What does a computer have to join a wireless LAN?
What is Bluetooth?